The concrete folks that did our basement were aware of the requirement and they simply left a stub sticking out of the floor next to the wall where the breaker panel was going to be located. I don't see how it will rust out being inside and dry, and not in contact with the earth. An inside stub seems to be the best situation re corrosion.
In addition, we have three ground rods plus the well casing which goes down 60' (the well is 320' deep).
